Dipper tooth



Patented Sept. 3, 1940 UNITED STATES FFME DIPPER TOOTH Lesher W. Van Busliirk, Easton, Pa. l

Application November 4, 1938, Serial No. 238,865

6 Claims. (Cl. 37I42) This invention relates to dipper teeth for power Fig. 2, illustrating in broken line the contour of shovels and the like and in particular to wear the tooth prior to service, and in iull line the points therefor, which usually are formed as reshape oi the tooth at the intermediate wear stage newable elements. y noted in Figures 1 and 2.

5 In service, the maximum wear on the point of Figure 4 is a transverse section on the line ll-li 5 a dipper tooth occurs at its front, and as the of Figure 2. tooth is customarily a solid wedge shaped body Figure 5 is a front end elevation of the tooth the point soon becomes dulled and blunt. Atpoint at the intermediate wear stage noted in tempts have been made to provide for a self- Figures l, 2 and 3.

sharpening action as the tooth wears by provid- In the disclosed embodiment of the invention 10 ing recesses in both the upper and lower tooth my improved tooth comprises a body 6 having faces so that a reduced thickness of metal is consubstantially straight sides l and a straight :front stantly presented at the front as the tooth wears or wear edge 3 extending transversely between away. While such a construction is effective in the sides, its rear edge portion being bifurcated in presenting a point, it becomes increasingly susthe usual manner to provide arms il by which 15 ceptible to curling or distortion due to the inthe tooth is secured to its support, not shown.

herent weakness resulting from the lack of rein- In side elevation the tooth is substantially forcement which is a concomitant of the rewedge-shaped, having its under face, or ground cessing. line i0, in a plane convergent with respect to the An object of the present invention is to protransverse axial plane H of the body and inter- 20 vide a self-sharpening dipper tooth point having, secting said axial plane substantially at the apex at all stages of wear, adequate reinforcement of the Wear point which, prior to service, coinagainst curling or distortion, so that the point cides with the front edge il as shown in Figure 1. efliciency is maintained and the point is inhibited In this respect the tooth follows conventional against curling or distortion over the entire wear practice. 25 life of the tooth. At its upper face or top the tooth departs from Another object is to provide a tooth wear point conventional practice which, in the case of a which, in addition to possessing the above charsolid tooth, usually embodies a flat top face in a acteristics, becomes progressively arcuate at its plane coincident with the line ma of Figure 1 3D wear edge in the transverse axial plane of the which is convergent to the axial plane Il. In 30 tooth as it wears away. l my improved form of tooth the entire top face l2 Still another object is to provide a dipper is crowned transversely and curved arcuately tooth having a self-sharpening point whereof the from front to rear in the axis of the tooth. This apex remains substantially in the transverse axial arrangement provides for an integral increased .5 plane of the tooth and at lsubstantially the same thickness of metal over the entire top face of the angle of incidence with respect to its ground line tooth. The under face of the tooth beginning at over the entire wearlife of the point. or near the front edge wear point t is formed An additional object is the provision of a selfwith a recess or channel I3 which extends axially sharpening dipper tooth having an axially of the tooth vbeing arcuate with respect to a c grooved under face and an upper face propor transverse plane passed through the tooth and tionately elevated to compensate the decrease being also substantially arcuate with respect to in thickness caused by the formation oi the the axis` of the tooth. The recess or channel i3 groove. constitutes a groove in the under face of the tooth Other objects will be readily apparent to those which runs from the front edge thereof entirely 15 skilled in the art. to the rear of the tooth body. The major depth 5 In the accompanying drawing: of the groove I3 occurs substantially at the mid- Figure 1 is an elevation, in full lines, of a tooth section of the tooth and proidmate the axis thereas formed in accordance with the invention, and of. From its point of greatest depth forwardly showing in broken line the shape of the tooth at the groove is arcuate in the axial plane of the an intermediate stage of its wear. tooth while from that point rearwardly the 50 Figure 2 is a top plan view of the tooth, illus grooved bottom assumes substantially a straight trating in dotted line the arcuate curvature ofthe line to the rear end of the tooth, as will be evipoint when worn to the intermediate stage noted dent from the illustration of Figure 1. in Figure 1. Figure l illustrates in broken line contour the Figure 3 is an axial section on the line 3-3 of coniiguration of the tooth when it has worn back 55 to the approximate mid-section. It will be seen that the wear point remains substantially at the transverse axial plane il of the tooth, the ground bearing line being deiined by the straight line portion of the bottom of the groove It which is convergent to the tooth axis i i at the wear point 8 at substantially the same angle at which the initial ground line l is convergent to the axis il at the initial Wear point 8. It should be remembered that as the tooth wears back the sides of the tooth wear away progressively so that the side walls of the groove i3 become progressively thinner and form, in effect, thin vertical cutting edges which play merely a negligible part in determining the ground bearing line of the tooth as they present insufficient horizontal surface to support the tooth body.

If the tooth were of the conventional solid type with no groove in its bottom face the ground bearing line would lie in the plane it when the Vvtooth had worn back to the intermediate point 3. It is evident that the ground bearing line in such case would be convergent to the tooth axis at a point spaced considerably in advance of the wear point 8', the effect being to dispose the point 8 considerably above the plane oi the ground bearing line so that as the tooth moved forward the elevated point would not bite into the material being excavated but on the contrary would tend to slide up on the material and thus lift the tooth without obtaining proper entry into the body of the material being excavated. n like manner the point would correspondingly become increasingly elevated. as the tooth wore back so that the tooth would become entirely ineiiective.

Further with reference to Figure l it will be noted that at the wear point B' the ground bearing line, being in the plane of the groove bottom i3, intersects the tooth axis substantially at the apex of the wear point so that the point rests on the ground as the tooth moves forward and at the proper angle for maximum entrance eiiiciency. This disposition of the wear point is eected automatically as the tooth progressively wears back and it is well illustrated in Figure 3, it being remembered that the vertical side walls of the groove are at such point merely thin substantially knife-like cutting edges. These edges thus penetrate the material to be dug.

it is thus evident that as the tooth wears back the wear point will be self-sharpening so that the maximum efficiency of the tooth is obtained over its entire life of wear.

An important feature of the invention resides in the fact that due to the crowning of the tooth over its top face l2, a sui'cient thickness oi metal is presented to provide adequate reinforcement resisting any tendency of the point to curl up or become distorted, and adds life to the sharp cutting tooth. As the high point of the crown .over the top face i2 coincides with a vertical plane passed through the axis of the tooth, which plane also coincides with the bottom oi the groove i3 in the underace, it is evident that the maximum thickness of reinforcing metal over the top face of the tooth occurs axially of the tooth in the line of greatest strain to which the wear point is subjected. This is well shown in Figure 5 in connection with Figure 2 wherein it is evident that when the tooth has worn back to the wear point 8 the cutting edge of the point is curved transversely of the tooth presenting an elliptical cutting edge which becomes progressively of increased curvature as the tooth Wears back. Thus, not only is the tooth automatically self-sharpening with respect to a vertical plane but with respect to a transverse axial plane, the combined effect of the two self-sharpening actions together with the presence of the groove I3 giving the precise self-sharpening vaction and form of an animals claw. c

A feature of the invention resides in the fact that the progressive rearward elevation of the top face i2 increases in proportion to the decrease in thickness cf the lower half of the tooth caused by the formation of the groove I3. Otherwise expressed, in form and location, the mass of the tooth body removed in providing the groove i3 is substantially transferred to and superimposed upon the top face l2, the maximum altitude of crowning occurring Substantially at the midsection of the tooth, at which point the groove i3 has substantially the greatest depth.

While in this illustrated embodiment I have disclosed a preferred form of the invention, it

understood that within the sco-pe of the invention as claimed, the structural details and arrangement oi parts may be varied as desired and substituted by any suitable equivalent.

Iclairn:

l. A dipper tooth comprising a body having a wear point at its front edge and extending transversely of the body, said body having substantially hat sides perpendicular to the wear point at the front of the body, the top and bottom faces of said body being divergent rearwardly "rom said wear point, said bottom face having formed therein an axially extending groove of arcuate form transversely of the body, and the top face of said body being integrally elevated as a crown extending from the wear point to the rear edge of the body with its niau'or height in the axis of the body at substantially its mid-section, the mass of the elevated portion ci said top face being substantially equal in buik and location to the mass of the body removed in forming said groove.

2. A dipper tooth comprising a substantially wedge shaped body provided on its under face with an axially extending groove of substantially arcuate cross section, and the upper face of said body being integrally thickened rearwardly substantially in proportion to the decrease of thickness at the under face resulting from the provision of the groove.

3. A dipper tooth comprising a wedge shaped body having on its under face an axially extending recess of substantially arcuate cross section and extending at its `sides to within a short distance of the sides of the body, and the upper face of said body being crowned transversely and axially substantially in proportion to the decrease of thickness at the underface resulting from the provision of the groove.

4. A dipper tooth comprising a substantially wedge shaped body having an axially disposed groove in its under face, the major depth of said groove being substantially at the mid-section of said body, and the top face of said body being integrally elevated in the axis of the body substantially in proportion to the decrease in thickness of the lower face caused by the formation of said groove.

5. A dipper tooth comprising a substantially wedge shaped body having an axially disposed Y greater thickness over substantially the midsection of the body than at any other point.

6. A dipper tooth comprising a substantially Wedge shaped body provided on its under face with an axially extending groove, and the upper portion of the body being progressively thickened axially and rearwardly of the tooth in proportion to and in conformity with the shape and depth of the groove, said groove extending substantially in parallelism to the thickened portion of the body.

LESHER W. VAN BUSKIRK. 

